INDIAN WELLS, Calif. — The last American man standing at the BNP Paribas Open will ascend to the No. 1 position in the nation's men's tennis race for the first time in his career.

California native Sam Querrey battled Australian Marinko Matosevic to a three-set victory 7-6 (7-5), 6-7 (7-9), 7-5 on Tuesday. That will elevate him into the top spot among Americans, and he should also break into the Top 20 ATP Tour rankings. The new rankings will be announced Monday.

Entering the tournament, Querrey was at No. 23, second overall in the U.S. to John Isner (No. 15), who is also his doubles partner. However, Isner needed to reach at least the quarterfinal round here to maintain that No. 1 slot. He did not, losing in three sets to Lleyton Hewitt in the second round.

The Serbian has won 20 consecutive matches now, dating to Oct. 31, when he lost to — none other Querrey — in the second round of the ATP World Tour Master 1000 Paris.

"I'm just going to hopefully play well, hopefully be aggressive, hopefully on those break points, deuce points, have some balls go my way," said Querrey. "I'm just going to try and just enjoy it out there."

Fellow American Mardy Fish, ranked No. 32 and behind Querrey in the American rankings as of this week, was quick to point out the difficulty of earning that No. 1 position.

Only the recently-retired Andy Roddick held the No. 1 spot in the nation and the world in 2004. Roddick's victory at the U.S. Open in 2003 was the last time an American won a Slam.

"Most everyone who has been the No. 1 American has been in the Top 10 as well so there are a lot of guys gunning for you," Fish said. "Sam's been out here for a while. He has been in a lot of situations, but it's kind of a shame. It sort of makes you appreciate Andy and what he did for 10 years just that much more. We're going to have a guy that might not even be in the top 20 and still the No. 1 American."

Querrey, however, will be among the top 20 in the world, possibly switching spots with Isner, and while Roddick watches from the sideline, it's Querrey who's been handed the American torch. If Querrey and Isner were to have lost early in the tournament, no American would have been among the Top 20 world rankings.

"It means a lot," Querrey said of reaching that mark. "I feel like I have worked hard to earn it. Everyone seems like they've got their shot with Andy and Mardy and James (Blake) and John, so I feel like it's my turn now."

He said those players have congratulated him, but he takes it in stride.

"I don't feel any different," he said. "I don't think they felt any different. It's another tournament next week, No. 1 American, No. 2 American, No. 3 American. I think if you're in the Top 10 you're seen a little differently."